Facile fabrication of 2D hetero core-satellites patterned Ag nanoparticle arrays with tunable plasmonic bands for SERS detection

A core-satellites metal nanostructure with high local electromagnetic (EM) intensity and density has shown great potential in ultrasensitive detection technologies, but complexity and uncontrollability of fabrication is a major obstacle for further application. Here, only by controlling the deposited Ag thickness, we facilely achieved 2D hetero core-satellites patterned Ag nanoparticle (NP) arrays for surface-enhanced Raman scattering (SERS) detection. The Ag nanoparticles were assembled by electron beam evaporation of Ag onto the anodized patterned aluminum template (APA1T) at a temperature above 0.24 times the melting point of Ag. The plasmonic bands can be continuously tuned from the visible to near-infrared region. The SERS enhancement factor (EF) and relative standard deviation (RSD) of as-prepared SERS active substrates for R6G molecules reached 10(7) and about 5%, respectively, and a SERS detection limit down to 10(-9) M was obtained. Finite-difference time-domain (FDTD) simulations revealed that the high SERS activity originates mainly from the local electromagnetic (EM) enhancement in the gaps between the core and satellites. The simple and controllable fabrication strategy and superior SERS performance make the 2D hetero core-satellites patterned Ag NPs arrays promising candidates for SERS-based sensor applications and provide a new approach for developing an inexpensive, efficient, and mass-produced SERS active substrate.